CN1273721A - Device and method for cancelling code interference in CDMA communication system - Google Patents
Device and method for cancelling code interference in CDMA communication system Download PDFInfo
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- H—ELECTRICITY
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- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7097—Interference-related aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7097—Interference-related aspects
- H04B1/7103—Interference-related aspects the interference being multiple access interference
- H04B1/7107—Subtractive interference cancellation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/02—Channels characterised by the type of signal
- H04L5/023—Multiplexing of multicarrier modulation signals
- H04L5/026—Multiplexing of multicarrier modulation signals using code division
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04J13/00—Code division multiplex systems
- H04J13/0007—Code type
- H04J13/004—Orthogonal
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- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03178—Arrangements involving sequence estimation techniques
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03178—Arrangements involving sequence estimation techniques
- H04L25/03248—Arrangements for operating in conjunction with other apparatus
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Abstract
A device and method for cancelling code interference in a receiver of a CDMA (Code Division Multiple Access) communication system simultaneously using orthogonal codes and quasi-orthogonal codes are provided. In a receiver according to an embodiment of the present invention, a channel estimator produces a channel estimation value of a pilot channel signal spread by an orthogonal code through despreading. A quasi-orthogonal channel receiver receives a channel signal spread by a quasi-orthogonal code, despreads the channel signal, demodulates the despread channel signal by use of the channel estimation value, and provides an output. An interference estimator estimates an interference value of the pilot channel signal with the channel signal spread by the quasi-orthogonal code by obtaining a correlation value between the orthogonal code corresponding to a pilot channel and the quasi-orthogonal code corresponding to a quasi-orthogonal channel. An interference canceller cancels the estimated interference from the output of the quasi-orthogonal channel receiver.
Description
Background of the present invention
1. the field of the invention
The present invention relates to a kind of apparatus and method that in CDMA (code division multiple access) communication system, are used to eliminate intersymbol interference (code interference), be particularly related to and be used at orthogonal code and quasiorthogonal code (QOC, quasiorthogonal code) exists simultaneously with in the cdma communication system of realizing channelizing, eliminate the apparatus and method of the mutual interference mutually between orthogonal code and the quasiorthogonal code.
2. description of related art
In cdma communication system, orthogonal code provides the channelizing of quadrature in all encoding channels, and the maximum number of available encoding channel is by the length decision of the longest orthogonal code.Walsh code (Walsh codes) is the typical orthogonal code of using in the cdma system, and therefore, hereinafter any the quoting to orthogonal code all relates to walsh code.Discharge up to calling out from call setup if specify an orthogonal channel with orthogonality to be exclusively used in a transmitter receiver, then the number of available channel just becomes very limited, and channel can not be distributed to each user.For making all users can both use cdma system, used quasiorthogonal code, though this is because it does not have orthogonality completely, it is with respect to other sign indicating number, the loss minimum of orthogonality.
For making the loss minimum of orthogonality, carry out " exclusive OR " with the longest orthogonal code of using in the system with the same long quasiorthogonal code mask with this longest orthogonal code, produce quasiorthogonal code.The series number of submitting on September 9th, 1998 is to have described the generation of binary quasi orthogonal code mask, the generation of quasiorthogonal code and the use of quasiorthogonal code in 09/149,924 the U.S. Patent application.The characteristics of quasiorthogonal code are the orthogonalities that can keep using between the orthogonal code code element of identical quasiorthogonal code mask, and use the loss of orthogonality minimum between the quasiorthogonal code of different quasiorthogonal code masks.
W
F1?XOR?W
F2?XOR?W
F3?XOR?W
·
·
·
FM?XOR?W
Wherein, W=N * N walsh matrix, the capable vector of Fi=1 * N.
(1). the accurate quadrature mask of 16 systems (16-ary) of size 512
F1＝77B4B477?774BB488?87BB4478?78BBBB78?77B44B88?774B4B7778444478?8744BB78
77B4B477?774BB488?87BB4478?78BBBB78?77B44B88?774B4B7778444478?8744BB78
F2＝7E4DDBE8?17244D7E?D41871BD?428E18D4?D4E77142?BD8EE7D47EB2DB17?E824B27E
7E4DDBE8?17244D7E?D41871BD?428E18D4?D4E77142BD8EE7D4?7EB2DB17?E824B27E
F3＝417214D87DB1281BEB274172D7E47DB1B17DE4D78DBED8141B28B17D?27EB8DBE
417214D8?7DB1281B?EB274172?D7E47DB1?B17DE4D78DBED814?1B28B17D?27EB8DBE
F4＝144EE441B114BEE44EEBBEE4144E1BBE8D287D27D78DD87DD78D2782?72D77D27
144EE441?B114BEE4?4EEBBEE4?144E1BBE?8D287D27D78DD87D?D78D2782?72D77D27
F5＝488B7B47?1DDED1ED?B88474B7?EDD1DE1D?122EDE1D477B74B7?1DDE2E12?488B84B8
488B7B47?1DDED1ED?B88474B7?EDD1DE1D?122EDE1D477B74B7?1DDE2E12?488B84B8
F6＝1DB78BDED17B47121D488B212E7BB8122E7B47ED1D4874DED17BB8ED?1DB77421
1DB78BDE?D17B4712?1D488B21?2E7BB812?2E7B47ED1D4874DE?D17BB8ED?1DB77421
(2). the accurate quadrature mask of 16 systems of size 256
F1＝77B4B477?774BB488?87BB4478?78BBBB78?77B44B88?774B4B7778444478?8744BB78
F2＝7E4DDBE817244D7ED41871BD428E18D4D4277142BD8EE7D47EB2DB17?E824B27E
F3＝417214D87DB1281BEB274172D7E47DB1B17DE4D78DBED8141B28B17D?27EB8DBE
F4＝144EE441B114BEE44EEBBEE4144E1BBE8D287D27D78DD87DD78D2782?72D77D27
F5＝488B7B47?1DDED1ED?B88474B7?EDD1DE1D?122EDE1D477B74B7?1DDE2E12?488B84B8
F6＝1DB78BDED17B47121D488B212E7BB8122E7B47ED1D4874DED17BB8ED?1DB77421
(3). the accurate quadrature mask of 16 row of size 128
F1＝17DBBD71?E8DB4271?17DBBD71?E8DB4271
F2＝72824EBE?BEB17D72?72824EBE?BEB17D72
F3＝2DEE87BB?8744D2EE?2DEE87BB?8744D2EE
(4). the accurate quadrature mask of 64 row of size 512
F1＝17DBBD71?E8DB4271
F2＝72824EBE?BEB17D72
F3＝2DEE87BB?8744D2EE
Use the quasiorthogonal code of above-mentioned quasiorthogonal code mask generation and the correlation between the walsh code to list in table 1.
Table 1
| Walsh code | ||||||||
| ????512 | ????256 | ????128 | ????64 | ????32 | ????16 | ????8 | ???4 | |
| ?QOS | ??512 | ?0，32 | ??16 | ?0，16 | ??8 | ??0，8 | ????4 | ??0，4 | ????2 |
| ??256 | ????- | ??16 | ?0，16 | ??8 | ??0，8 | ????4 | ??0，4 | ????2 | |
| ??128 | ????- | ???- | ?0，16 | ??8 | ??0，8 | ????4 | ??0，4 | ????2 | |
| ??64 | ????- | ???- | ?????- | ??8 | ??0，8 | ????4 | ??0，4 | ????2 |
Basic orthogonal code is defined as carrying out " exclusive OR " to produce quasiorthogonal code and to have indicated the orthogonal code of walsh code with the quasiorthogonal code mask.Walsh code can be from the different layers of different length, as long as they can guarantee orthogonal channelization in encoding channel.Yet,, preferably the walsh code of basecoat or the longest walsh code are used as basic orthogonal code for the their cross correlation that utilizes table 1 to provide fully.Here, the length with basic orthogonal code is defined as L.
Fig. 1 is to use the theory diagram of the transmitter in the cdma communication system of above-mentioned quasiorthogonal code.With reference to Fig. 1, label 140 and 170 typical channel encoder of representative and interleavers.Signal mapper 112,142, and 172 " 0 " and " 1 " that will import data be transformed to signal level "+1 " and " 1 " respectively.Demultiplexer 144 and 174 is separated into I-channel data and Q-channel data to traffic channel data, sends so that carry out QPSK (quaternary PSK).Demultiplexer 144 and 174 can be serial-to-parallel transducer (SPC).Under the situation of traffic channel data being carried out BPSK (binary phase shift keying) modulation, then omit demultiplexer 144 and 174, and, on an I channel and a Q channel, send data.
Walsh code code element W # 0 generator 116 produces the sign indicating number walsh code code element W # 0 as basic orthogonal code, so that pilot channel is carried out spread spectrum.Pilot channel is used for the channel estimating of receiver.Frequency mixer 118 so that pilot frequency channel signal is carried out orthogonal spectrum expansion, is delivered to adder 162 to the output of walsh code code element W # 0 generator 116 and the output multiplication of signal mapper 112 to the pilot frequency channel signal behind the orthogonal spectrum expansion then.The walsh code code element W #A that walsh code code element W #A generator 146 produces as basic orthogonal code.Frequency mixer 148 and 158 multiplies each other the output of walsh code code element W #A generator 146 and the I channel data and the Q channel data that receive from demultiplexer 144, to produce spread-spectrum signal.Gain controller 150 and 160 control Traffic Channels are with respect to the relative gain of pilot channel.
The walsh code code element W #a that walsh code code element W #a generator 176 produces as basic orthogonal code.Quasiorthogonal code mask M #m generator 186 produces the quasiorthogonal code mask that is used for producing from basic orthogonal code quasiorthogonal code.Frequency mixer 178 and 188 is the output multiplication of walsh code code element W #a generator 176 and quasiorthogonal code mask M #m generator 186, produce thus and belong to quasiorthogonal code Q[m] quasiorthogonal code code element Q[m] #a, and, frequency mixer 178 and 188 is also quasiorthogonal code code element Q[m] and the I channel and the Q channel data that receive from demultiplexer 174 multiply each other, thereby to quasiorthogonal code code element Q[m] carry out spread spectrum.Gain controller 180 and 190 is controlled with the relative gain of the Traffic Channel behind the quasiorthogonal code spread spectrum with respect to pilot channel.Adder 162 and 192 is respectively I channel signal and the addition of Q channel signal, and output S_I[n] and S_Q[n].PN (Pseudo Noise, pseudo noise) code generator 120 produces two PN sequence PN_I[n that are used for multiple PN spread spectrum] and PN_Q[n].Multiple PN frequency multiplier 130 then carries out multiple PN spread spectrum with the output of PN code generator 120 to the output of adder 162 and 192.
(S_I[n]+jS_Q[n])(PN_I[n]+jPN_Q[n])
＝(S_I[n]PN_I[n]-S_Q[n]PN_Q[n])+j(S_I[n]PN_Q[n]+S_Q[n]PN_I[n])
I channel signal in the signal behind the multiple PN spread spectrum (S_I[n] PN_I[n]-S_Q[n] PN_Q[n[) and the Q channel signal (S_I[n] PN_Q[n]+S_Q[n] PN_I[n]) be applied to the input of low pass filter (LPF) 164 and 194 respectively.The size of amplifier 166 and 196 transmission signals is adjusted to the level of expection.Carrier generator 122 produces the frequency that sends signal upwards is converted to the required carrier wave of high frequency.90 ° of phase shifters 124 produce 90 ° phase difference at I channel and Q interchannel.Carrier wave is multiply by in the output of frequency mixer 168 and 198 pair amplifiers 166 and 196, to modulate sending signal.Adder 126 is modulated I channel and the addition of Q channel signal, and then, transmitting antenna 128 is launched the output of adder 126.
Fig. 2 is to use the block diagram of the conventional receiver in the cdma system of quasiorthogonal code.The modulation signal that reception antenna 228 receives from transmitter.Carrier generator 222 produces the frequency down-conversion of received signal to the required carrier wave of fundamental frequency.90 ° of phase shifters 224 produce 90 ° phase difference at I channel and Q interchannel.Frequency mixer 268 and 298 multiply by carrier wave to received signal, and with demodulation, the high fdrequency component that timing produces is separated in LPF264 and 294 filterings then, and only allows baseband signal pass through.
Usually, in the mobile radio environment, the path that the signal that sends from transmitter can arrive receiver exists a plurality of.Yet signal receiving structure is identical to each path.
Therefore, will signal receiving structure be described according to a path here.
PN (pseudo noise) code generator 220 produces the PN sequence PN_I[n with process demodulated received signal synchronised] and PN_Q[n].Signal and the PN sequence of the following algorithm steps of multiple PN despreader 230 usefulness after to low-pass filtering calculated:
(S_I[n]PN_I[n]-S_Q[n]PN_Q[n])+j(S_I[n]PN_Q[n]+S_Q[n]PN_I[n])
(PN_I[n]+jPN_Q[n])
＝(S_I[n]+jS_Q[n])(PN_I[n]+jPN_Q[n])(PN_I[n]+jPN_Q[n])
＝S_I[n]+jS_Q[n]
The signal of the multipath after the demodulation of 202 pairs of above-mentioned receiving mechanisms of process of combiner makes up.Deinterleaving and channel-decoding are carried out in the output of deinterleaver and 200 pairs of combiners 202 of channel decoder.
Because orthogonal code and quasiorthogonal code coexistence, there is loss of orthogonality in above-mentioned conventional receiver at interchannel.Therefore, the phase mutual interference that reduces between orthogonal code and the quasiorthogonal code is impossible.
General introduction of the present invention
An object of the present invention is to provide a kind of apparatus and method of interference of the signal that cancellation receiver receives in cdma communication system.
Another object of the present invention provides orthogonal code that a kind of loss of orthogonality of eliminating the signal that receives owing to receiver in the cdma communication system of orthogonal code and quasiorthogonal code coexistence the causes apparatus and method to the interference of quasiorthogonal code.
A further object of the present invention provides quasiorthogonal code that a kind of loss of orthogonality of eliminating the signal that receives owing to receiver in the cdma communication system of orthogonal code and quasiorthogonal code coexistence the causes apparatus and method to the interference of orthogonal code.
For achieving the above object, use at the same time in the cdma communication system of orthogonal code and quasiorthogonal code a kind of receiver is provided.In receiver according to an embodiment of the invention, channel estimator produces channel estimation value with the pilot frequency channel signal of orthogonal code spread spectrum by despreading.Accurate orthogonal channel receiver receives the channel signal with the quasiorthogonal code spread spectrum, and this channel signal is carried out despreading, and the channel signal after using channel estimation value to despreading then carries out demodulation, and output is provided.Interference estimator by obtain the orthogonal code corresponding with pilot channel and with the corresponding quasiorthogonal code of accurate orthogonal channel between correlation, come the interference value of estimating pilot frequency channel signal to the channel signal of usefulness quasiorthogonal code spread spectrum.Interference eliminator is eliminated the interference of estimating from the output of accurate orthogonal channel receiver.
Brief description of drawings
In conjunction with the drawings the preferred embodiments of the present invention are described in detail, above-mentioned purpose of the present invention and advantage will become apparent, wherein:
Fig. 1 is to use the block diagram of the transmitter of the prior art in the cdma communication system of orthogonal code and quasiorthogonal code;
Fig. 2 is to use the block diagram of the receiver of the prior art in the cdma communication system of orthogonal code and quasiorthogonal code;
Fig. 3 according to the first embodiment of the present invention, be used to eliminate with the pilot channel of orthogonal code spread spectrum to block diagram with the receiver of the interference of the Traffic Channel of quasiorthogonal code spread spectrum;
Fig. 4 be according to a second embodiment of the present invention, be used to eliminate with the pilot channel of orthogonal code spread spectrum to block diagram with the receiver of the interference of the Traffic Channel of quasiorthogonal code spread spectrum;
Fig. 5 is a third embodiment in accordance with the invention, be used to eliminate with the channel of orthogonal code spread spectrum to the block diagram with the receiver of the interference of the Traffic Channel of quasiorthogonal code spread spectrum; And
Fig. 6 is the fourth embodiment of the present invention, be used to eliminate with the channel of quasiorthogonal code spread spectrum to the block diagram with the receiver of the interference of the Traffic Channel of orthogonal code spread spectrum.
Detailed description of preferred embodiment
Below with reference to accompanying drawings the preferred embodiments of the present invention are described in detail.In the drawings, the identical identical parts of label representative.
Receiver of the present invention can use orthogonal code and quasiorthogonal code simultaneously in cdma communication system, and can eliminate the interference between orthogonal code and the quasiorthogonal code.Whole transmitters in the cdma system use identical transmitting power, and the quality of reception can improve, and can keep the quality of reception by the transmitting power that reduces transmitter.
Fig. 3 according to the first embodiment of the present invention, be used to eliminate with the pilot channel of orthogonal code spread spectrum to block diagram with the receiver of the interference of the Traffic Channel of quasiorthogonal code spread spectrum;
As described in background one joint of the present invention, the modulated signal that reception antenna 228 receives from transmitter.Carrier generator 222 produces the frequency down conversion of received signal to the required carrier wave of base band frequency.90 ° of phase shifters 224 produce 90 ° phase difference at I signal and Q interchannel.Frequency mixer 268 and 298 multiply by carrier wave to received signal, with demodulation.Then, LPF264 and 294 removes and separates the high fdrequency component that timing produces, and only allows baseband signal pass through.
Usually, in the mobile radio environment, the path that the signal that sends from transmitter can arrive receiver exists a plurality of.Yet signal receiving structure is identical to each path.
Therefore, will signal receiving structure be described according to a path here.
(S_I[n]PN_I[n]-S_Q[n]PN_Q[n])+j(S_I[n]PN_Q[n]+S_Q[n]PN_I[n])
(PN_I[n]+jPN_Q[n])
＝(S_I[n]+jS_Q[n])(PN_I[n]+jPN_Q[n])(PN_I[n]+jPN_Q[n])
＝S_I[n]+jS_Q[n]
The pilot channel that channel estimator 210 uses by walsh code code element W # 0 spread spectrum is carried out channel estimating to each path.Walsh code code element W # 0 generator 216 produces walsh code code element W #0.Frequency mixer 214 carries out complex multiplication to the output of multiple PN despreader 230 and the output of walsh code code element W # 0 generator 216.The add up output of the frequency mixer 214 in each predetermined period of time of accumulator 212 is to extract channel estimation value.For this reason, accumulator 212 can substitute with a LPF.This channel estimation value is used for Traffic Channel is carried out demodulation.By the quasiorthogonal code code element Q[m that is used for Traffic Channel is multiply by in the output of multiple PN despreader 230] #a, can obtain the data of Traffic Channel.
Multi-path signal after the demodulation of 202 pairs of above-mentioned receiving mechanisms of process of combiner makes up.Deinterleaving and channel-decoding are carried out in the output of deinterleaver and 200 pairs of combiners 202 of channel decoder.
As mentioned above, 310 pairs of channel estimation values of frequency mixer multiply by its complex conjugate, with produce from the channel estimation value of channel estimator 210 outputs square, and then multiply by-C
0, a m, wherein, C
0, a mBe defined as:
Formula 1:
Then, adder 320 is removed the estimated value of this channel to the interference of Traffic Channel from demodulated traffic channel signal.As prior art, glitch-free signal is output to combiner 202.According to the first embodiment of the present invention, receiver is as shown in Figure 3 estimated the interference of this channel to the channel of use quasiorthogonal code, eliminates the interference of estimating then from the channel that uses demodulated quasiorthogonal code.
Except that above-mentioned interference eliminated, all processes that this receiver is carried out is identical with the receiver among Fig. 2.
Fig. 4 be according to a second embodiment of the present invention, be used to eliminate with the pilot channel of orthogonal code spread spectrum to block diagram with the receiver of the interference of the Traffic Channel of quasiorthogonal code spread spectrum.Receiver among Fig. 4 and the receiver among Fig. 3 are basic identical in structure and operation, and different is, the former comprises device 410, be used for directly from channel estimation value derive channel estimation value square.
Fig. 5 is a third embodiment in accordance with the invention, be used to eliminate with the channel of orthogonal code spread spectrum to the block diagram with the receiver of the interference of the Traffic Channel of quasiorthogonal code spread spectrum.To describe receiver shown in Figure 5 below, emphasis is described the elimination of the channel of use orthogonal code to the interference of the Traffic Channel of use quasiorthogonal code.Ignore description at this to the general operation of this receiver.
Hadamard transform Hadamard transformation device (Hadamard transformer) 530 calculates the output of multiple PN despreader 230 according to following formula fast:
Formula 2:
In cdma communication system, be not all to be used by all basic orthogonal codes that formula 2 defines.The output of the quick Hadamard transform Hadamard transformation device 530 of the walsh code code element input that therefore, is used for not being used is caused by noise.The value of noise component(s) is littler than the value of the walsh code code element in using.Therefore, determinant 520 compares the output and the predetermined value θ of quick Hadamard transform Hadamard transformation device 530, if the former is littler than the latter, judges that then the former is a noise.If the walsh code code element is littler than predetermined value θ, just the value with the walsh code code element is defined as 0, reduce thus The noise (if | d
i|＜0, d then
i=0).
Then, arithmetic unit 510 uses the vector of the output of 3 pairs of determinants 520 of formula to multiply by (1) and the quasiorthogonal code Q[m that is used for Traffic Channel] vector that amasss of correlation between #a and its corresponding walsh code:
Formula 3:
Wherein, m is a quasiorthogonal code mask number, and α is the basic orthogonal code that is used to produce quasiorthogonal code, and L is the length of orthogonal code.
Fig. 6 is a fourth embodiment in accordance with the invention, be used to eliminate with the channel of quasiorthogonal code spread spectrum to the block diagram with the receiver of the interference of the Traffic Channel of walsh code spread spectrum.
In the receiver of Fig. 6, there is not the quasiorthogonal code mask generator 286 of Fig. 5, this receiver is used to receive the information of the Traffic Channel of using walsh code.Hadamard transform Hadamard transformation device 630 calculates the output of PN despreader 230 again according to formula 4 fast:
Formula 4
As top description, be not all to be used by cdma system by all quasiorthogonal codes that formula 4 defines about Fig. 5.The output of the quick Hadamard transform Hadamard transformation device 630 of the walsh code code element input that therefore, is used for not being used is caused by noise.The value of noise component(s) is littler than the value of the quasiorthogonal code code element in using.Therefore, determinant 620 compares output and a predetermined value θ of quick Hadamard transform Hadamard transformation device 630, if the former is littler than the latter, judges that then the former is a noise.If the quasiorthogonal code code element is littler than predetermined value θ, just the value with the quasiorthogonal code code element is defined as 0, reduce thus The noise (if | d
i m|＜0, d then
i m=0).
Then, arithmetic unit 610 uses the vector of the output of 5 pairs of determinants 620 of formula to multiply by the vector that amasss of the correlation between (1) and the walsh code W# that is used for Traffic Channel and its corresponding quasiorthogonal code:
By using different quasiorthogonal code masks, can produce a plurality of quasiorthogonal codes from a basic orthogonal code.In system, quasiorthogonal code can each self-corresponding orthogonal code use with them.If used a plurality of quasiorthogonal codes, the proportional increase of number of the number of then above-mentioned receiver mechanism and the quasiorthogonal code mask of use.Like this, adder 640 is sued for peace to the amassing of the estimated value of the interference of the Traffic Channel of use Wal sign indicating number code element W#A to (1) and the channel that uses quasiorthogonal code.The output that frequency mixer 310 multiply by adder 640 to the complex conjugate of the channel estimation value that receives from complex conjugate device 206.Here, the output of frequency mixer 310 is to use the accurate interference components of handing over the channel of sign indicating number to the channel of the use orthogonal code of their correspondences.Then, adder 320 is by the output of frequency mixer 310 and the demodulated traffic channel signal addition that receives from frequency mixer 204, eliminates the interference to the Traffic Channel of use walsh code code element W#A of the channel that uses quasiorthogonal code.Then glitch-free traffic channel signal is applied to the input of combiner 202.
As mentioned above, in orthogonal code and the common cdma communication system that exists of quasiorthogonal code, receiver of the present invention detect since the orthogonal code that the loss of orthogonality of interchannel causes to quasiorthogonal code or quasiorthogonal code to the interference of orthogonal code, and from corresponding channel, remove interference.Like this, all transmitters use identical transmitting power, and receiver also can obtain the quality of reception preferably.And the transmitting power that reduces transmitter still can reach the identical quality of reception.
Although with reference to certain embodiments the present invention is described in detail above, they only are exemplary application.Therefore, should be expressly understood that those skilled in the art can carry out multiple change within by scope of the present invention that claims limited and aim.
Claims (15)
1, a kind of receiver that in CDMA (code division multiple access) communication system, uses orthogonal code and quasiorthogonal code simultaneously, described receiver comprises:
Channel estimator is used for by the channel estimation value of despreading generation by the pilot frequency channel signal of orthogonal code spread spectrum;
Accurate orthogonal channel receiver is used to receive the channel signal by the quasiorthogonal code spread spectrum, and this channel signal of despreading uses the channel signal of this this despreading of channel estimation value demodulation, and output is provided;
Interference estimator, be used for by obtain with the corresponding orthogonal code of pilot channel and and the corresponding quasiorthogonal code of accurate orthogonal channel between correlation, come the interference value of estimating pilot frequency channel signal to the channel signal of usefulness quasiorthogonal code spread spectrum; And
Interference eliminator is used for eliminating the interference of estimating from the output of described accurate orthogonal channel receiver.
2, receiver as claimed in claim 1, wherein, described interference eliminator comprises:
The complex conjugate device is used to calculate the complex conjugate of the output of described channel estimator;
First multiplier is used for complex conjugate is multiply by in the output of described channel estimator; And
Second multiplier is used for coming the estimating pilot frequency channel to aim at the interference value of orthogonal channel by the output multiplication of described correlation and described first multiplier.
3, receiver as claimed in claim 1, wherein, described interference eliminator comprises:
Squarer is used for the output of described channel estimator is asked square; And
Multiplier is used for coming the estimating pilot frequency channel to aim at the interference value of orthogonal channel by the output multiplication of described correlation and described squarer.
4, receiver as claimed in claim 1, wherein, described correlation calculates by following formula:
Wherein, i is the walsh code that is used for pilot channel, and j is the basic orthogonal code that is used to produce quasiorthogonal code, and m is the quasiorthogonal code mask, and L is the length of orthogonal code.
5, a kind of receiver that in CDMA (code division multiple access) communication system, uses orthogonal code and quasiorthogonal code simultaneously, described receiver comprises:
PN (pseudo noise) despreader is used for carrying out to the received signal the PN despreading;
Accurate orthogonal channel receiver is used for the signal of quasiorthogonal code despreading PN despreading;
Interference estimator is used for estimating the interference value of orthogonal code to the quasiorthogonal code channel according to the signal of PN despreading; And
Interference eliminator is used for eliminating the interference value of estimating from the output of described accurate orthogonal channel receiver.
6, receiver as claimed in claim 5, wherein, described interference estimator comprises:
The Hadamard transform Hadamard transformation device is used to detect orthogonal code code element that is not used and the orthogonal code code element that is used fast;
Determinant is used for the output of described quick Hadamard transform Hadamard transformation device and predetermined value are compared also, removes the orthogonal code code element that is not used; And
Arithmetic unit is used for the vector of the output of described determinant be multiply by the quasiorthogonal code of accurate orthogonal channel and the correlation between the corresponding orthogonal code, to produce the interference value of orthogonal code to the estimation of quasiorthogonal code channel.
7, receiver as claimed in claim 6, wherein, described quick Hadamard transform Hadamard transformation device detects the orthogonal code code element that is not used by following formula:
And described arithmetic unit is estimated interference value by following formula:
Wherein, m is a quasiorthogonal code mask number, and α is the basic orthogonal code that is used to produce quasiorthogonal code, and L is the length of orthogonal code.
8, receiver as claimed in claim 6, wherein, described interference eliminator comprises:
Multiplier is used for the complex conjugate of the output of arithmetic unit and pilot channel estimation value is multiplied each other; And
Adder is used for the output of removing described multiplier from described accurate orthogonal channel receiver.
9, a kind of receiver that in CDMA (code division multiple access) communication system, uses orthogonal code and quasiorthogonal code simultaneously, described receiver comprises:
The PN despreader is used for carrying out to received signal the PN despreading;
The orthogonal channel receiver is used for the signal of orthogonal code despreading after the PN despreading;
Interference estimator is used for estimating the interference value of quasiorthogonal code to basic orthogonal code according to the signal after the PN despreading; And
Interference eliminator is used for eliminating the interference value of estimating from the output of described orthogonal channel receiver.
10, receiver as claimed in claim 9, wherein, described interference estimator comprises:
Fast the Hadamard transform Hadamard transformation device is used for carrying out computing by the quasiorthogonal code code element to the signal after the PN despreading, distinguishes the orthogonal code code element that is not used and the orthogonal code code element of use;
Determinant is used for the output and the predetermined value of described quick Hadamard transform Hadamard transformation device are compared, and removes the orthogonal code code element that is not used; And
Arithmetic unit is used for the vector of the output of described determinant be multiply by the orthogonal code of orthogonal channel and the vector of the correlation between the corresponding quasiorthogonal code, with the interference value of the estimation that produces quasiorthogonal code.
11, receiver as claimed in claim 10, wherein, described quick Hadamard transform Hadamard transformation device detects the orthogonal code code element that is not used by following formula;
And described arithmetic unit is estimated interference value by following formula:
Wherein, m is a quasiorthogonal code mask number, and A is the orthogonal code of using in the described orthogonal code channel receiver, and L is the length of orthogonal code.
12, receiver as claimed in claim 10, wherein, described interference eliminator comprises:
Multiplier is used for the complex conjugate of the output of described arithmetic unit and pilot channel estimation value is multiplied each other; And
Adder is used for removing from described orthogonal channel receiver the output of multiplier.
13, eliminate the method for intersymbol interference in a kind of receiver that uses orthogonal code and quasiorthogonal code in cdma communication system, comprise the following steps:
By the channel estimation value of despreading generation by the pilot frequency channel signal of orthogonal code spread spectrum;
Reception is by the channel signal of quasiorthogonal code spread spectrum, this channel signal of despreading, and use channel signal after this this despreading of channel estimation value demodulation;
By obtain and the corresponding orthogonal code of pilot channel and and the corresponding quasiorthogonal code of accurate orthogonal channel between correlation, come the estimating pilot frequency channel signal to interference value by the channel signal of quasiorthogonal code spread spectrum; And
From the accurate orthogonal dispreading channel signal of demodulation, eliminate the interference value of estimating.
14, a kind ofly use orthogonal code and quasiorthogonal code in cdma communication system and receive the method for eliminating intersymbol interference in the receiver with the channel signal of quasiorthogonal code spread spectrum, described method comprises the following steps:
With the device that the orthogonal code code element of the signal after the PN despreading is carried out quick Hadamard transform Hadamard transformation, distinguish orthogonal code code element that is not used and the orthogonal code code element that is used.
The output and the predetermined value of the device that the orthogonal code code element is carried out quick Hadamard transform Hadamard transformation are compared, and remove the orthogonal code that is not used;
The vector of having removed the signal of the orthogonal code code element that is not used be multiply by the quasiorthogonal code of accurate orthogonal channel signal and the vector of the correlation between the corresponding orthogonal code, and produce the interference value that orthogonal code is aimed at the estimation of orthogonal channel signal; And
From accurate orthogonal channel signal, remove the interference value of estimating.
15, a kind ofly use orthogonal code and quasiorthogonal code in cdma communication system and receive the method for eliminating intersymbol interference in the receiver by the channel signal of orthogonal code spread spectrum, comprise the following steps:
Distinguish the orthogonal code that is not used and be used orthogonal code with the device that the signal after the PN despreading is carried out quick Hadamard transform Hadamard transformation;
The output and the predetermined value of Hadamard transform Hadamard transformation are fast compared, and remove the orthogonal code code element that is not used;
The vector of having removed the signal of the orthogonal code that is not used be multiply by the orthogonal code of orthogonal channel signal and the vector of the correlation between the corresponding quasiorthogonal code, and produce the interference value of quasiorthogonal code the estimation of quadrature channel signal; And the interference value of from the orthogonal channel signal, removing estimation.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019980027736A KR100318959B1 (en) | 1998-07-07 | 1998-07-07 | Apparatus and method for eliminating interference between different codes in a CDMA communication system |
| KR1998/27736 | 1998-07-07 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1273721A true CN1273721A (en) | 2000-11-15 |
| CN1119883C CN1119883C (en) | 2003-08-27 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN99801088A Expired - Fee Related CN1119883C (en) | 1998-07-07 | 1999-07-07 | Device and method for cancelling code interference in CDMA communication system |
Country Status (11)
| Country | Link |
|---|---|
| US (1) | US6459693B1 (en) |
| EP (1) | EP1021882B1 (en) |
| KR (1) | KR100318959B1 (en) |
| CN (1) | CN1119883C (en) |
| AU (1) | AU729216C (en) |
| BR (1) | BR9906577A (en) |
| CA (1) | CA2302340C (en) |
| DE (1) | DE69929029T2 (en) |
| IL (1) | IL134887A (en) |
| RU (1) | RU2213423C2 (en) |
| WO (1) | WO2000002397A2 (en) |
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-
1998
- 1998-07-07 KR KR1019980027736A patent/KR100318959B1/en not_active IP Right Cessation
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- 1999-07-07 IL IL13488799A patent/IL134887A/en not_active IP Right Cessation
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101610234B (en) * | 2003-01-07 | 2012-04-25 | 高通股份有限公司 | Pilot transmission schemes for wireless multi-carrier communication systems |
| CN113162723A (en) * | 2016-11-14 | 2021-07-23 | 拉姆帕特通信有限责任公司 | Reliable orthogonal spreading codes in wireless communications |
| US11838078B2 (en) | 2019-09-24 | 2023-12-05 | Rampart Communications, Inc. | Communication system and methods using very large multiple-in multiple-out (MIMO) antenna systems with extremely large class of fast unitary transformations |
Also Published As
| Publication number | Publication date |
|---|---|
| EP1021882B1 (en) | 2005-12-21 |
| DE69929029T2 (en) | 2006-06-22 |
| CA2302340C (en) | 2006-05-30 |
| US6459693B1 (en) | 2002-10-01 |
| CA2302340A1 (en) | 2000-01-13 |
| IL134887A (en) | 2004-02-08 |
| CN1119883C (en) | 2003-08-27 |
| AU729216B2 (en) | 2001-01-25 |
| AU4656299A (en) | 2000-01-24 |
| KR20000008080A (en) | 2000-02-07 |
| WO2000002397A2 (en) | 2000-01-13 |
| RU2213423C2 (en) | 2003-09-27 |
| DE69929029D1 (en) | 2006-01-26 |
| IL134887A0 (en) | 2001-05-20 |
| WO2000002397A3 (en) | 2000-03-30 |
| KR100318959B1 (en) | 2002-04-22 |
| AU729216C (en) | 2001-10-18 |
| EP1021882A2 (en) | 2000-07-26 |
| BR9906577A (en) | 2000-12-05 |
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